Wafer handling apparatus are generally utilized to transfer wafers from one transporting vehicle to another. These transporting vehicles are normally referred to as a "boat". In a typical manufacturing environment, there is a moving boat for transporting the wafers between processing stations. At processing stations, the wafers need to be transferred into a quartz boat which is utilized with the actual processing. This is normally carried out with a wafer transfer apparatus which is disclosed in U.S. Pat. No. 4,695,217, issued Sept. 22, 1987, which U.S. Patent is incorporated herein by reference.
One processing technique to increase efficiency is that utilizing a "back-to-back" configuration. In a back-to-back configuration, wafers which are to be processed on only one side are transferred into a quartz boat and then another set of wafers are also transported into the same boat except that the second set of wafers are aligned with the first set of wafers with adjoining wafers having the backs thereof disposed adjacent to each other. With this configuration, it is not necessary to coat or protect the backs, since they are protected from any processing. Therefore, it is important that the wafers are in close proximity to each other.
In a back-to-back configuration, handling is of the utmost importance. When disposing two wafers in close proximity to each other, there is always the possibility of scratching the surface of the wafer. Typically, the wafers have been placed in the boat by hand to insure that the backs of adjoining wafers are closely aligned with each other and, upon separation, a manual operation is also performed, whereby tweezers or some sort of mechanical separator is inserted between the two wafers. This can lead to wobbling of a given wafer and contact with an adjoining set of wafers, which contact would be very undesirable.
There therefore exists a need for a wafer handling apparatus that will both position wafers in a back-to-back configuration and then separate the wafers without incurring any damage to the process surface of the wafer.